After almost three decades, the iconic slackers played by Keanu Reeves and Alex Winter are all grown up and ready to hop back in their time machine for a third film in the cult comedy franchise. Fans are celebrating the occasion by making #BillAndTedDay go viral on Twitter.

“Happy Bill and Ted Day Everyone!!!,” one amped up fan tweets. “Today is the day to be excellent, especially to one another.”

Meanwhile, other fans encourage tweeters to incorporate franchise slang into Shakespeare quotes along with this hashtag: #replacebardquotewithDUDE.

Yeah, it’s safe to say social-media watchdogs have been slobbering for this promo trailer since the B&T reboot was announced last summer.

“We wanna say thank you to you the fans,” Reeves, 55, says in the promo clip released when production launched in March 2019. “It’s all because of you guys and we owe you a huge debt of gratitude, so thank you — and be excellent,” Winter, 54, chimes in.

The official “Face the Music” plot synopsis: “Yet to fulfill their rock and roll destiny, the now middle-aged best friends set out on a new adventure when a visitor from the future warns them that only their song can save life as we know it. Along the way, they will be helped by their daughters, a new batch of historical figures, and a few music legends — to seek the song that will set their world right and bring harmony in the universe.”

The sequel picks up where 1991’s “Bill & Ted’s Bogus Journey” left off — but, of course, “the stakes are higher than ever.” Hey, it’s produced by Oscar winner Steven Soderbergh and directed by Dean Parisot (“Galaxy Quest”), so we wouldn’t expect anything less.

“Bill & Ted’s Excellent Adventure” premiered in 1989, introducing the teen buds who are on the verge of failing out of high school if they don’t pass their upcoming history report.

With the threat of Ted’s dad sending him off to military school — and breaking up their band, Wyld Stallyns — as punishment, the pals recruit time-traveler Rufus (George Carlin) to help them ace the assignment. Along the way they meet a host of historical figures — from Sigmund Freud to Joan of Arc — and the rest is cinematic history.

Will this long-belated sequel pass the test with die-hard fans? We’ll have to wait until the film’s Aug. 21, 2020, release date to find out.